Regular physical activity substantially reduces the risk of dying of coronary heart disease, the nation's leading cause of death, and decreases the risk for stroke, colon cancer, diabetes, and high blood pressure. It also helps to control weight; contributes to healthy bones, muscles, and joints; reduces falls among older adults; helps to relieve the pain of arthritis; reduces symptoms of anxiety and depression; and is associated with fewer hospitalizations, physician visits, and medications. Moreover, physical activity need not be strenuous to be beneficial; people of all ages benefit from participating in regular, moderate-intensity physical activity, such as 30 minutes of brisk walking five or more times a week.

Despite the proven benefits of physical activity, more than 50% of American adults do not get enough physical activity to provide health benefits. 25% of adults are not active at all in their leisure time. Activity decreases with age and is less common among women than men and among those with lower income and less education. For detailed information about adult U.S. physical activity levels among demographic groups in a state or metropolitan area, search the U.S. Physical Activity Statistics database.

Insufficient physical activity is not limited to adults. More than a third of young people in grades 9–12 do not regularly engage in vigorous-intensity physical activity. Daily participation in high school physical education classes dropped from 42% in 1991 to 32% in 2001 (CDC, 2002).